Puffer power plant

ABSTRACT

A vehicle-powering gas turbine of the gas-coupled type includes a power transfer clutch between the gas generator turbine and the power turbine of the engine. To use the power plant for blowing air for such purposes as unloading powdered cargo, a bleed from the outlet of the engine compressor is opened and the power turbine is decoupled from the vehicle power transmission and drive wheels and coupled to the gas generator turbine by the power transfer clutch.

United States Patent 1191 Flanigan et al.

[ Nov. 13, 1973 1 PUFFER POWER PLANT [75] Inventors: Eugene E. Flanigan,Carmel; Roger W. Merriman, Indianapolis, both of Ind.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

221 Filed: Mar. 20, 1972 211 Appl. No.: 236,328

[52] US. Cl. 4l7/319, 60/39.l6 R, 60/39.18 C, 180/66 A, 417/374 [51]Int. Cl. F041) 9/00 [58] Field of Search 60/39.l8 C, 39.16 R, 60/39.33,39.51 R;417/47, 16, 381, 319,

374; 180/66 A, 66 B, 53 R [56] References Cited UNITED STATES PATENTS3,609,967 10/1971 Waldmann 60/39.18 C

AIR

FUEL CONTROL ing? Z6 3,635,019 1/1972 Kronogard (SO/39.16 3,237,4043/1966 Flanigan et a1... 60/39.16

3,587,766 6/1971 Slade 180/66 A 3,418,806 12/1968 Wagner et al.....60/39.51 R

6/1970 Austin 60/39.16

Primary Examiner-Carlton R. Croyle Assistant Examiner-Warren OlsenAttorney-Paul Fitzpatrick et al.

[57] ABSTRACT A vehicle-powering gas turbine of the gas-coupled typeincludes a power transfer clutch between the gas generator turbine andthe power turbine of the engine. To use the power plant for blowing airfor such purposes as unloading powdered cargo, a bleed from the outletof the engine compressor is opened and the power turbine is decoupledfrom the vehicle power transmission and drive wheels and coupled to thegas generator turbine by the power transfer clutch.

4 Claims, 2 Drawing Figures TRANS.

CLUTCH PUFFER POWER PLANT Our invention is directed to the provision ofa gas turbine engine particularly suited to provide shaft output powerfor such purposes as driving a vehicle such as a truck ortractor-trailer combination, for example, and also for supplying airunder pressure in considerable quantities for desired purposes, such asfor blowing particulate cargo from such a vehicle.

It is well known that compressed air may be derived from the compressorof a gas turbine, whether a turbojet, turboprop, or turboshaft engine.However, no substantial amount of air may be bled from the ordinary gasturbine without seriously upsetting the energy balance of the engine. Ifa shaft driving gas turbine engine is properly balanced to deliver themaximum shaft power output under maximum permissible turbine inlettemperature, it is not possible to bleed a great proportion of the airfrom the compressor of the engine. The bleeding causes a mismatch of theturbine and compressor and there is insufficient motive fluid to drivethe turbine under the compressor load. In a gas turbine solely for thepurpose of pumping air, the compressordriving turbine is intended toextract all possible energy from the air compressed in the compressorand heated in the engine combustion apparatus, and the system isbalanced for use with the relatively large diversion of air from thecompressor-combustor-turbine circuit.

There are circumstances in which it is desirable for a gas turbine to beadaptable both to providing shaft power and to supplying substantialquantities of compressed air. One of these is use with a vehicle whichis driven by the gas turbine power plant and which is adapted to haul apowdered, particulate, or granular cargo which may be discharged fromthe vehicle by an airlift system. This may be the case whether thevehicle is a tractor-trailer outfit or other vehicle, including boats. I

It has been proposed in the past to provide com.- pressed gas fordischarging such cargo by using the exhaust of a reciprocating engine,by employing air driven by an auxiliary compressor separate from thevehicle power plant, and by pumping air with a compres sor driven by aturbine powered by the exhaust from a reciprocating engine; this last isdisclosed in U.S. Pat. No. 3,495,766 of Hinkle, Feb. 19, 1970. BritishPat.

No. 736,318 of Collins, Sept. 7, 1955 and U.S. Pat. No.,

2,769,500 of Clifi'ord, Nov. 6, 1956 propose bleeding compressed airfrom gas turbines installed in motor vehicles.

Our invention is directed to the use of the compressor of a gas turbinepower plant adapted for vehicle propulsion as a means for providingcompressed air for blowing cargoes or other purposes. Briefly stated, inour invention the power turbine of such an engine is coupled to the gasgenerator turbine for supply of energy from the power turbine to the gasgenerator turbine at the time the engine is used for pumping air.

The engine may be of a well known type such as those described inCollman et al. U.S. Pat. No. 3,267,674 issued Aug. 23, 1966 or Bell U.S.Pat. No. 3,490,746 issued Jan. 20. 1970. Such engines include a powertransfer mechanism which provides for clutching the gas generator andpower turbines together, this power transfer being the subject ofFlanigan et al. U.S. Pat. No. 3,237,404 issued Mar. 1, 1966.

The power transfer system of the Flanigan et al. patent was conceived ofprimarily as a means to transfer power from the gas generator turbine tothe power turbine to improve efficiency of the power plant at partloads. It also serves as means to transfer power from the power turbineto the gas generator turbine to prevent runaway of the power turbinewhen decoupled from the load and to-provide dynamic braking ofthevehicle propelled by the engine.

The principal objects of our invention are to provide an improved powerplant for vehicle propulsion and supply of compressed air, to utilize acoupling between the gas generator turbine and power turbine in agascoupled gas turbine engine as a means for augmenting the input to theengine compressor for the purpose of bleeding air from the compressorfor use outside the power plant and, in general, to provide a simplebleed air or compressed air supply feature in a vehicle propulsion powerplant without substantial modification of the power plant or prejudiceto its utility as a vehicle propulsion power plant.

The nature of our invention and its advantages will be clear to thoseskilled in the art from the succeeding detailed description of preferredembodiments and the accompanying drawings.

FIG. 1 is a schematic diagram of a gas turbine power plant incorporatingthe invention.

FIG. 2 is a partial schematic diagram illustrating a modification. v

Referring to FIG. 1, a compressor 2 receives atmospheric air anddischarges it through a conduit 3 to one pass of a heat exchanger 4 inwhich the air is heated by heat exchange from the engine exhaust. Theheat compressed air then flows through conduit 5 to combustion apparatus6 in which fuel is burned, and the resulting combustion products aresupplied to a high pressure turbine 7 which is connected through a draft8 to drive compressor 2. The compressor, combustion apparatus, andturbine constitute a gas generator. The exhaust from turbine 7 issupplied throughducting 9 as illustrated to the power turbine 10. Thepower turbine drives a power'output shaft 11, illustrated as connectedthrough a clutch 12 to a transmission l4and' so to a load 15 which maybe vehicle' driving wheels. The clutch may, of course, be a part of thetransmission 14, and the transmission may be a manually shiftablegearbox or some form of automatic transmission. The exhaustfrom thepower turbine flows through ducting 16, through the other pass of heatexchanger 4, and to an exhaust pipe 18.

The heat exchanger 4 may be omitted, but it is a highly desirablefeature in such power plants. A shaft 19 driven by the gas generatorturbine and a shaft 20 driven by the power turbine may be coupled fortransmission of power by means indicated schematically as a clutch 22.As described in the patents mentioned above, ordinarily the powerturbine operates at somewhat lower speed than the gas generator turbineso that the' actual connection between the two involves some gearing.The details of this are immaterial to our present invention. a I

The operationv of the engine'is controlled by a'fuel control 24 whichmay be regulated by an arm 26 connected, for example, to a footthrottle'or hand throttle control in the vehicle. Fuel is supplied underpressure by a suitable pump (not illustrated) to the fuel control, whichmeters the desired quantity of fuel to the engine to assure operation atthe desired power level and prevent overspeed, overtemperature, and soon, as is well known to those skilled in the art. The fuel is suppliedfrom the fuel control to the combustion apparatus through a fuel line27. The fuel control receives an input of gas generator speed through ashaft 28 driven by shaft 8 and an input of gas generator turbine inlettemperature from a thermocouple 30. It may receive other inputs whichare immaterial to the present discus- In the illustrated embodiment, theclutches 12 and 22 are engaged by oil under pressure, and the basicelements of one suitable oil system are illustrated in FIG. 1. An oilpump 31 which takes oil from a suitable sump is driven by shaft 32 fromthe gas generator turbine. Pump 31 may supply oil through lines 34 to apower transfer control 35, to a normally closed valve 36, and to anormally open valve 38. The normally open valve 38 is disposed ahead ofa clutch control 39 which controls supply of clutch engaging oil to thehydraulic cylinder 40 of clutch 12.. Supply of oil to this cylindercauses the plates of the clutch to engage and transmit power. Aspreviously mentioned, the clutch 12 may be a part of the powertransmission 14 and the clutch control 39 a part of the control of suchtransmission. Automatic transmissions have some provision to shift theminto neutral so that the engine is decoupled from the load.Alternatively, a valve connected to dump oil from the clutch 12 whenenergized might be used.

Valve 38 may be closed by a solenoid 42 energized from the vehicle powersupply, represented by battery 43, through a manually operable switch44. Switch 44 energizes a line 46 to energize solenoid 42 and closevalve 38, which interrupts supply of engaging oil to clutch 12, causingit to become disengaged. Obviously, more sophisticated schemes forcontrol of the clutch may be present, or the clutch may be simplydisengaged manually when desired.

The power transfer control 35 may operate generally as described in theabove-mentioned Flanigan et a1. patent to control supply of oil underpressure to an engaging cylinder 47 of the clutch 22. The normallyclosed valve 36 may be opened by a solenoid 48 energized from line 46 asone possible means to provide a supply of oil under pressure from pump31 to the engaging cylinder 47 to couple the two turbines togetherregardless of the operation of the power transfer control 35. If thepower transfer clutch automatically engages when power turbineoverspeeds, valve 36 will not be required. When the throttle is advancedand clutch 12 is disengaged, clutch 22 will engage, as described in theFlanigan et al. patent.

As illustrated, the bleed air system includes a branch line 50 from thecompressor discharge conduit 3 which is connected through a normallyclosed valve 51 to the compressed air delivery line 52. Valve 51 isshown as opened by a solenoid 54 energized through line 46 from theswitch 44. Normally, some controllable valve, indicated at 53, will bedisposed at the point of use of the air. I

It will be seen, therefore, that closing of switch 44 interruptstransmission of power from the power turbine to the transmission anddrive wheels, couples the power turbine to the gas generator turbinethrough clutch 22, and opens valve 51 to allow delivery of air to thesupplied device, which is not illustrated here. Clearly, it is notessential for all of these controls to be coupled to a single actuatingdevice such as switch 44, but this is a suitable and convenient way toaccomplish the desired result. It is desirable to have an interlock toprevent opening air valve 51 unless the power transfer clutch is engagedor will engage automatically as explained above,

With the two turbines so coupled, the power extracted from the gasgenerator turbine exhaust by the power turbine makes availablesufficient power to drive the compressor notwithstanding the loss of airto the discharge circuit. About one-fourth of the air compressed may bebled.

A specific operative embodiment of the invention, in an engine rated at280 shaft horsepower and having an airflow rating of 4 pounds persecond, is capable of pumping 1 pound per second of air at 25 psig at1700F. turbine inlet temperature. This is accomplished at about percentfull rated turbine speed. The engine may be governed at the desiredspeed through the governing means in the fuel control operated throughshaft 28.

FIG. 2 illustrates a possible modification of the engine. In FIG. 2 thesystem may be as illustrated in FIG. 1 except that FIG. 2 illustratesmeans to derive bleed air from the engine which has been heated in theheat exchanger 4. There may be situations in which a supply of quite hotair would be desired for some purpose. In this case, the conduit 3' fromthe compressor feeds the compressed air through one pass of heatexchanger 4 into a duct 5' leading to the combustion apparatus 6. Abranch duct 56 from duct 5' leads through normally closed valve 58,opened by the solenoid 54 of FIG. 1, and permitting discharge of hotcompressed air through a discharge line 60. It will be appreciated, ofcourse, that the air delivered by the compressor is reasonably warm fromcompression and thus in most cases the additional heating will not beneeded or even desirable.

In practice, in either version of the system, the control may besimplified when the power transfer control includes means forautomatically coupling the power turbine to the gas generator if thepower turbine overspeeds. In this case, disengagement of the normal loadwill lead to overspeed of the power turbine and engagement of the clutch22 when the gas generator is operating.

It should be clear from the foregoing to those skilled in the art thatthe engine and system described herein is particularly well suited tomeet the objectives of providing propulsion for a vehicle or shaft powerfor other purposes and providing compressed air for any desired purpose.Some of the purposes for which such compressed air may be used includesexpelling from a tank trailer pulverized or liquid cargo such as cement,fly ash, liquid fertilizers, small grains, fuel oils and hotdistillates, plastic pellets, etc. The bled air could also be used foroperation of an air motor for driving any form of auxiliary device suchas apump, compressor, generator, or alternator.

The detailed description of the preferred embodiments of the inventionfor the purpose of explaining the principles thereof is not to beconsidered as limiting or restricting the invention, since manymodifications may be made by the exercise of skill in the art.

We claim:

1. A gas turbine power plant for alternatively powering a power outputshaft and supplying air under pres sure for auxiliary purposescomprising, in combination,

an air compressor, combustion apparatus supplied by the compressor, afirst turbine supplied with motive fluid by the combustion apparatus andcoupled to drive the compressor, a second turbine rotatableindependently of the first turbine and supplied by the combustionapparatus, the second turbine being connectable to drive the poweroutput shaft; means for disconnecting the second turbine from the poweroutput shaft and coupling the turbines for transfer of power from thesecond turbine to the first turbine; and means for bleeding aircompressed by the compressor from the engine while the turbines are socoupled.

2. A gas turbine power plant for alternatively powering a vehicle andsupplying air under pressure for blowing cargo from the vehiclecomprising, in combination, an air compressor, combustion apparatussupplied by the compressor, a first turbine supplied with motive fluidby the combustion apparatus and coupled to drive the compressor, asecond turbine rotatable independently of the first turbine and suppliedby the combustion apparatus, the second turbine being connectable todrive the vehicle; means for disconnecting the second turbine from thevehicle drive and coupling the turbines for transfer of power from thesecond turbine to the first turbine; and means for bleeding aircompressed by the compressor from the engine while the turbines are socoupled.

3. A gas turbine power plant for alternatively powering a vehicle andsupplying air under pressure for auxiliary purposes comprising, incombination, an air compressor, combustion apparatus supplied by thecompressor, a first turbine supplied with motive fluid by the combustionapparatus and coupled to drive the compressor, a second turbinerotatable independently of the first turbine and supplied by thecombustion apparatus, the second turbine being connectable to drive thevehicle; a regenerator for heating the compressed air by the turbineexhaust; means for disconnecting the second turbine from the vehicledrive and coupling the turbines for transfer of power from the secondturbine to the first turbine; and means for bleeding air compressed bythe compressor and heated by the regenerator from the engine while theturbines are so coupled.

4. A gas turbine power plant for alternatively powering a vehicle andsupplying air under pressure for auxiliary purposes comprising, incombination, an air compressor, combustion apparatus supplied by thecompressor, a first turbine supplied with motive fluid by the combustionapparatus and coupled to drive the compressor, a second turbinerotatable independently of the first turbine and supplied by thecombustion apparatus, the second turbine being connectable to drive thevehicle; means for disconnecting the second turbine from the vehicledrive and coupling the turbines for transfer of power from the secondturbine to the first turbine; and means for bleeding air compressed bythe compressor from the engine while the turbines are so coupledincluding interlock means effective to prevent bleeding air when theturbines are not so coupled.

1. A gas turbine power plant for alternatively powering a power outputshaft and supplying air under pressure for auxiliary purposescomprising, in combination, an air compressor, combustion apparatussupplied by the compressor, a first turbine supplied with motive fluidby the combustion apparatus and coupled to drive the compressor, asecond turbine rotatable independently of the first turbine and suppliedby the combustion apparatus, the second turbine being connectable todrive the power output shaft; means for disconnecting the second turbinefrom the power output shaft and coupling the turbines for transfer ofpower from the second turbine to the first turbine; and means forbleeding air compressed by the compressor from the engine while theturbines are so coupled.
 2. A gas turbine power plant for alternativelypowering a vehicle and supplying air under pressure for blowing cargofrom the vehicle comprising, in combination, an air compressor,combustion apparatus supplied by the compressor, a first turbinesupplied with motive fluid by the combustion apparatus and coupled todrive the compressor, a second turbine rotatable independently of thefirst turbine and sUpplied by the combustion apparatus, the secondturbine being connectable to drive the vehicle; means for disconnectingthe second turbine from the vehicle drive and coupling the turbines fortransfer of power from the second turbine to the first turbine; andmeans for bleeding air compressed by the compressor from the enginewhile the turbines are so coupled.
 3. A gas turbine power plant foralternatively powering a vehicle and supplying air under pressure forauxiliary purposes comprising, in combination, an air compressor,combustion apparatus supplied by the compressor, a first turbinesupplied with motive fluid by the combustion apparatus and coupled todrive the compressor, a second turbine rotatable independently of thefirst turbine and supplied by the combustion apparatus, the secondturbine being connectable to drive the vehicle; a regenerator forheating the compressed air by the turbine exhaust; means fordisconnecting the second turbine from the vehicle drive and coupling theturbines for transfer of power from the second turbine to the firstturbine; and means for bleeding air compressed by the compressor andheated by the regenerator from the engine while the turbines are socoupled.
 4. A gas turbine power plant for alternatively powering avehicle and supplying air under pressure for auxiliary purposescomprising, in combination, an air compressor, combustion apparatussupplied by the compressor, a first turbine supplied with motive fluidby the combustion apparatus and coupled to drive the compressor, asecond turbine rotatable independently of the first turbine and suppliedby the combustion apparatus, the second turbine being connectable todrive the vehicle; means for disconnecting the second turbine from thevehicle drive and coupling the turbines for transfer of power from thesecond turbine to the first turbine; and means for bleeding aircompressed by the compressor from the engine while the turbines are socoupled including interlock means effective to prevent bleeding air whenthe turbines are not so coupled.